THE native white-clawed crayfish is in trouble. Threatened by the American signal crayfish, the native species has now been lost from large parts of the UK and is classified by the International Union for Conservation of Nature (IUCN) as endangered.

Experts say Yorkshire is now on the frontline of the battle between the two, and projects are underway to try and safeguard the native species.

The white-clawed crayfish has an appearance similar to a miniature lobster, feeds on plant and animal matter and detritus, and is most active at night.

There is a population in the river at Fountains Abbey, near Ripon, but its continued existence is threatened by a population of the invasive American signal crayfish, discovered upstream of the abbey in 2015.

The American crayfish could not have established itself upstream of the abbey’s native population without having been accidentally or deliberately released there by people.

Earlier this year, a number of the white-clawed crayfish were moved from the River Skell at Fountains Abbey to a new safe location in a joint scheme between the Environment Agency and the National Trust.

The creatures' new home is upstream above a reservoir dam, which is high enough to prevent signal crayfish reaching the site from downstream.

All the crayfish being moved were examined by Environment Agency experts to ensure they were native white claws and not one of their very similar looking American cousins.

Tim Selway, Environment Agency biodiversity officer, says: “Native crayfish have the same conservation status as blue whales and Siberian tigers. It is sad to think that this crayfish population, living here since before the World Heritage Site of Fountains Abbey was built, is now likely to be lost due to people having illegally released signal crayfish upstream.”

He adds: “Yorkshire is now on the frontline between native white-clawed crayfish and American signal crayfish.

“The native crayfish population has now been given a chance to survive in this new location."

AMERICAN signal crayfish were introduced to Britain in the 1970s an attempt to diversify farming. However, they escaped into the wild, where they thrived. They now pose the most significant threat to the survival of native crayfish.

This is mainly due to a fungal disease they can carry called ‘crayfish plague’ which is harmless to American crayfish (and humans) but is fatal to the native species.

American crayfish are also hardier and more efficient feeders than natives, which are unable to hold their own in the face of competition from them.

Once American crayfish have been released into a river, there is no practical way to remove them. Trapping them has been shown to actually increase their numbers as traps tend to attract large males, but these would normally keep the population in check by cannibalising smaller signal crayfish.

Stephen Morley, wildlife and countryside adviser for the National Trust, says action was needed to try and help the native species survive.

“It’s sad to see the native white-clawed crayfish under threat at Fountains Abbey and Studley Royal, but this is the right course of action to help aid the future survival of the species," he explains.

“We’d been monitoring the crayfish – native and non-native species – in the River Skell for some years. Thankfully, this close monitoring helped us to pinpoint locations of the best areas to find significant populations of native crayfish in the river, meaning that they could be successfully collected and moved to a safer habitat for them to thrive.”

Under the Wildlife and Countryside Act, it is illegal to take native white-clawed crayfish from their habitat. The same legislation makes it an offence to release non-native species of crayfish into the wild.

The use of any type of crayfish as bait for fishing is also illegal. Trapping crayfish requires consent from the Environment Agency. Consent for personal or commercial purposes is not granted in Yorkshire in order to protect the remaining populations of natives.

Trapping risks people spreading crayfish plague and unwittingly catching native crayfish.

Spores of crayfish plague can be spread by contaminated boats, fish and fishing equipment.

All water users are advised to follow the Environment Agency’s advice of ‘Check, Clean and Dry’ when they have finished using their equipment to prevent the spread of signal crayfish and plague.